1. Field of the Invention
The present invention relates to an eye ball detecting device which can detect the presence/absence of an observer's eye and, more particularly, to an eye ball detecting apparatus which detects the presence/absence of an observer's eye on the basis of an eye ball image.
2. Related Background Art
Conventionally, U.S. Pat. No. 5,138,354 discloses a camera which uses a switch arranged in the grip portion of the camera, and a light-emitting element and a light-receiving element arranged in the finder portion, and turns on the switch in the grip portion when a user holds a camera to look into a finder. On the other hand, U.S. Pat. No. 5,200,774 discloses a camera which can detect the approach of a user's face to a finder by utilizing a technique for detecting the approach of an object by receiving light emitted from a light-emitting element and reflected by the object. Also, Japanese Laid-Open Patent Application No. 3-192338 filed by the present applicant discloses an observation apparatus which can discriminate, based on a received image signal, if an approaching object is an eye ball.
However, in the cameras disclosed in U.S. Pat. Nos. 5,138,354 and 5,200,774 as the prior art, the grip switch cannot be correctly operated depending on the holding state of the camera, and the grip shape is considerably limited so as to reliably operate the grip switch.
On the other hand, since the approach or proximity detection technique for detecting the presence/absence of light reflected by an object responds to any object present near the finder, operation errors often occur in response to an object other than the eye ball.
In the eye ball detection technique which is disclosed in Japanese Laid-Open Pat. Application No. 3-192338 and can detect the eye ball on the basis of a received image, whether or not an approaching object is an eye ball can be discriminated based on an image signal, and operation errors can be eliminated. However, in order to obtain a detection result by processing an image obtained by an area sensor, a large-capacity memory for storing the data of a large number of two-dimensionally distributed pixels, and calculation means for calculating data at high speed are required. The consumption power of the calculation means becomes inevitably large.